Double superphosphate - concentrated phosphate fertilizer . The main phosphorus-containing component is calcium dihydroorthophosphate monohydrate Ca ( H 2 P O 4 ) 2 · H 2 O. It usually also contains other calcium and magnesium phosphates. In comparison with simple phosphate does not contain ballast - CaSO 4 . The main advantage of double superphosphate is a small amount of ballast, that is, it reduces transportation costs, storage costs, packaging [1] .
Content
- 1 Receiving
- 2 Production in Russia
- 3 notes
- 4 Sources
Getting
Double superphosphate is produced by the action of phosphoric acid on natural phosphates: . In Russia, the flow method is mainly used: the decomposition of raw materials, followed by granulation and drying of the resulting pulp in a drum granulator dryer. Commodity double superphosphate from the surface is neutralized with chalk or NH 3 to obtain a standard product. A certain amount of double superphosphate is produced by the chamber method. The phosphorus-containing components are basically the same as in simple superphosphate, but in larger quantities, and the CaSO 4 content is 3-5%. When heated above 135-140 ° C, double superphosphate begins to decompose and melt in crystallization water, after cooling it becomes porous and brittle. At 280–320 ° C, orthophosphates transform into meta , pyro , and polyphosphates , which are in assimilable and partially water-soluble forms. It melts at 980 ° C, turning after cooling into a glassy product in which 60-70% of metaphosphates are citrate-soluble. Double Superphosphate contains 43-49% of assimilable phosphoric anhydride (phosphorus pentoxide) P 2 O 5 (37-43% water-soluble), 3.5-6.5% of free phosphoric acid H 3 PO 4 (2.5-4.6% P 2 O 5 ):
Ca 3 (PO 4 ) 2 + 2H 2 SO 4 = Ca (H 2 PO 4 ) 2 + 2 CaSO 4
There is also a method of decomposing phosphorus-containing raw materials with phosphoric acid :
Ca 5 (PO 4 ) 3 F + 7H 3 PO 4 = 5Ca (H 2 PO 4 ) 2 + HF
Production in Russia
In Russia, double superphosphate is produced in accordance with GOST 16306-80 of two grades. Grade A is made from Khibiny apatite concentrate or Moroccan phosphorites with a mass fraction of total phosphates of at least 32.5%. Grade B is made from Baltic phosphorites with a mass fraction of phosphates of at least 28%. In the finished product, the phosphorus anhydride content is 45–47 and 42–44%, respectively.
Notes
- ↑ Kaputsky F.N., Tikavy V.F. Chemistry manual for applicants to universities. - Minsk: Higher School, 1979. - S. 218.
Sources
- The article "SUPERPHOSPHATES" on xumuk.ru by:
- Chepelevetsky M. L., Brutkus E. B., Superphosphate. Physico-chemical bases of production, M., 1958;
- Karmyshov V.F., Chemical processing of phosphorites, M., 1983; Double superphosphate, L., 1987
- Double superphosphate // Great Soviet Encyclopedia : [in 30 vol.] / Ch. ed. A.M. Prokhorov . - 3rd ed. - M .: Soviet Encyclopedia, 1969-1978.